This post explains why the Windows 7 USB/DVD Download Tool (WUDT) is unable to copy the install files to the USB drive in some cases. The tool allows you to create a copy of your Windows 7 ISO file on a USB flash drive.

Michael Pietroforte is the founder and editor of 4sysops. He is a Microsoft Most Valuable Professional (MVP) with more than 30 years of experience in system administration.

Update: If you have problems Windows 7 USB/DVD Download Tool you can try the free alternative Rufus. The most powerful tool for creating a bootable Windows setup flash drive is WinSetupFromUSB.

You might have heard of the stir that Microsoft’s Windows 7 USB/DVD Download Tool (WUDT) caused last year when some Open Source watchmen recognized that the tool contained code that violated the GPL. Microsoft was then “forced” to release WUDT under GPLv2. Considering the upset in the media about this incident, I expected a luxurious tool that comes with lots of customization features. I was somewhat disappointed to discover it does nothing else but copy the contents of a Windows 7 install DVD to a USB stick and make it bootable.

The funny thing is that WUDT even failed to perform this simple task with my no-name USB stick. This message was the only thing that the Open Source tool could do for me:

We were unable to copy your files. Please check your USB device and the selected ISO file and try again.

At least, my cheap stick wasn’t the cause because everything worked perfectly when I manually did the job (hopefully without violating any Open Source laws). So, I thought, I would write this post for those who might run into the same problems and think they need to buy another USB stick. After all, this is Microsoft software and there are not many options to integrate bugs in such a simple tool.

Anyway, here is what you have to do. Launch a command prompt with admin rights and run the diskpart tool. Note: Before you run these commands read the warning below!

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diskpart

list disk

select disk#

clean

create partition primary

select partition1

active

format quick fs=fat32

assign

exit

The “list disk” command will show you the connected drives and with “select disk”, you can choose your USB stick.

WARNING: Be careful to select the right drive or else your day won’t have a happy end because if you select the wrong drive you will lose all your data on this drive!

The crucial step here is the “clean” command. It overwrites the MBR and the partition table (thereby, deleting everything on the stick). My guess is that WUDT misses this step and only formats the flash drive. It appears my memory stick had some odd partitions (which is not uncommon). When I tried WUDT again with this prepared stick, the Open Source tool mastered its task without further murmur.

By the way, this is also the reason why you shouldn’t use the Windows Disk Management applet to prepare the USB stick. This GUI doesn’t offer a clean command.

After you prepare the stick, you have to copy the contents of your Windows 7 DVD to the thumb drive, and you are done. If you only have an ISO file, you can use Virtual CloneDrive to mount the Windows 7 install DVD first.

Instead of formatting the partition with FAT32, you can also use NTFS (like WUDT does), but then you need an extra step to make the drive bootable:

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Bootsect.exe/nt60X:

“X:” is the drive letter of your USB stick. Bootsect.exe can be found on the Windows 7 DVD in the boot folder. However, I can’t really recommend using NTFS. My USB stick, at least, appeared to be slower with NTFS.

I recently had the same problem with this MS tool, The solution was quite simple: disable Avira (free antivirus tool)! It turns out that the antivirus software detects malicious activities on the usb device (surprise, we are trying to make it bootable & copy stuff like autorun.inf!).

So if you see this “can’t copy files”, try to disable your antivirus software!

I made a Google Chromium OS boot disk on my USB drive and it created half a dozen non windows partitions. Disk manager was having problems even deleting them, I got another program to remove them and used Windows to reformat it but it was the MBR that was causing problems.

Thank you! Had the exact same problem, found this through Google. Quite lame that Windows’ disk management doesn’t offer the “clean” option in the GUI and that the WUDT doesn’t realize where the error lies.

Wow. Seems that I’m the only idiot who can’t get it to work. I tried with diskpart, which seems to do what it is supposed to do, but to no effect. Tried the HP Tool, but that won’t work either. Turned off the antivirus software (ESET), but there’s nothing to be done. It just won’t give in.

My USB Stick is from Lexar (8gb). Any chance I missed something important? Or is there a possibility that some sticks just won’t work no matter what?

My experience just so if you don’t get it to work, you don’t have to go mad and pull your hair out:

I think some sticks just don’t work, no matter what. With two sticks I tried everything mentioned here and then some, but no use. Then, I tried two other sticks and the first one worked right away and the second had to be prepared the way you explained.

Works a treat. Getting the unable to copy files error. Tried running through the diskpart steps but would not recognise the USB stick as I was using an XP machine. Tried installing the MS tool on a Win7 machine and retried the steps. After following your series of DISKPART commands the ISO copy tool works perfectly. Thaks for fixing a very frustrating problem.

Also in my case, WUDT report: “We were unable to copy your files. Please check your USB device and the selected ISO file and try again.” I disabled my free antivirus Avira and all worked well (as Rene Treffer written above). Avira blocked a file named “autorun.inf” written on USB stick and everything went wrong from that point.

Thanks a lot man , it did work for me haha , I was getting the ” unable to copy ” error , then I used your steps plus disabled the WUDT to format my USB creating a new register in regedit and it finally creates my Win7 Sp1 usb copy

If you are displeased with the Microsoft tool, try the Win To Flash tool from: http://wintoflash.com/home/en/ it works flawlessly for creating a boot-able Windows install usb drive. It also supports other versions of windows like Vista and XP.

I had the same problem. What was strange is that I had installed Win 7 in other computer using the same USB and ISO file; and that I could still do it with another USB. So I formated, checked for errors in the drive, etc. and nothing worked. Then I found your article, and the solution, with the plus of a satisfying explanation of the problem. Thank you very much, my friend!

Worked! Every drive I tried to install the windows 8 pre-release refused to work. I tried 3 different drives and kept getting errors. As soon as I tried this method it finally worked. I am now installing Windows on my tablet! It’s odd that Microsoft never added the clean option to that program.

Saved the day! Thanks a lot. I’ve used WUDT a few times before and it worked, then all of a sudden it didn’t. I was driving myself crazy trying to figure out what was wrong… I’ve formatted and reformatted to no avail. Then I came across this post and all the positive responses so I had to try it. It worked, thanks again.

Thank heavens I found this article, just like one of the guys here said about plugging the pen drive in the xbox 360 it’s true. I had it in when I was having a Gears of War 3 marathon between two places, so I used my flash drive for my saves. When using this tool to use it for WUDT, it just would not budge. This guide did the trick, but I did have to use the HP USB Format Tool since even DISKPART was telling me “Well your USB is in a pickle right now so…NOPE”.

But after using the HP tool and then WUDT, life was good again. My laptop is finally ready for a trip to Windows 7!

MANY thanks for the guide and to the peoples comments with helpful pointers!

Greetings, and thanks for the instructions–they were awesome for a computer-illiterate person! After completing the file copy, I got a message saying that the files was copied…”however, drive is not bootable”. Hmm… any suggestions? I’m hoping to install W7 to my new SSD. Thanks!

For me it was my antivirus software. The WUDT log file was filled with this message: “Error during backup., Usb; Access to the path ‘X:\autorun.inf’ is denied.”. I disabled my Trend Micro AV and it worked like a charm!

The logfile can be found @ Users\\AppData\Local\Apps\Windows 7 USB DVD Download Tool\Log

Thank you for this… You should make this known to Microsoft because I was on the phone with tech support for 3 hours talking to multiple “experts” and none could figure out why this was happening… One of them did explain how to clean the drive and stuff which I already knew how to do anyways.. My only question was why it KEPT recorruing… They don’t know that if you use the drive in an Xbox 360, you need to go through these steps in order to get it to be used by another program created by them. Cross compatibility between Xbox & Windows sould be pretty close when handling things like “Formatting” — Anyways, thank you for finally making it clear to me what was causing it at least..

Mike, I don’t know about the issues that the others were facing. I was just looking for a way to install Win 7 from a thumb drive & I stumbled across your article.

I tried the steps u mentioned, & it worked like a charm, no dramas at all. I’ve just completed the stages up to the point where you unpack the contents of the ISO file to the thumb drive. So far, so good. Now, I’ll try to install Win 7 on my other computer with the thumb drive. I’ll update the results whether I succeed or not.

Thank you, my good man, the advice you provided was accurate and successfully resolved my issue. It seems that the Microsoft provided tool is unable to cope with drives >32GB, as it will not format them with the FAT32 partition table. Manually creating the boot disk using NTFS was the solution. Your guide provided me with the missing link; the bootsec.exe step was one that I had missed.

Thanks for the commands. The reason why this error message appears at my installation was that avira antivirus tool blocked the autorun.inf of the windows iso-file I tryed to copy to the USB stick. Unchecking this function in the antivirus tool made WUDT doing its job.

Just deactivate the “block autorun” function of you firewall and /or anti virus software. i´m using avira antivir as antivirus program and had the same problem. after deactivation of the block autorun function it just went well.. cheers

Very surprised the ‘clean’ command has no GUI access anywhere within windows. Obviously there shouldn’t be anyone fiddling with it willy-nilly, but what common consumer goes into the Disk Management within control panel anyway? Should have been added.

Thanks, it works. But I have a strange problem.. My have 8GB USB drive. Earlier it was showing 7.45GB usable. but now its 7.43GB usable after using diskpart. (* I had used “clean” command). Does anyone knows why?

HI, I have done the booting of computer before with the same usb drive. Now i am having this error problem and i have done all the step you have written. Still, it does not work for me. Please help me.

Here’s an update to my post above. The WUDT kept failing with 99% completed. After giving up, I happened to notice all of the files were happily waiting on the USB drive. Just for fun, I ran the setup to see what would happen. Setup completed successfully!

Thanks a lot Michael! This worked perfectly. I had the same problem as the first poster Luke, I had used a Kingston G2 flash drive several times with WUDT but today it just would not work. After following your instructions it worked the first time.

Guys make sure you have disabled your antivirus! I am using Avira Free antivirus and when I perform the procedure, the program become failed! After disabling my Avira the program done its job perfectly!

Watch out! The WinToFlash utility recommended halfway thru the comments, loads a ton of spyware on your windows even when you choose NO, DO NOT INSTALL during the installation. OptimizerPro, LiveSupport, Search, etc. Use something else!

It worked, finally something does!!!!! Now I can reinstall Win7, then I hopefully won’t get the bootstrapper error message when trying to load MS Office 2013. A Win 7 reinstall, is my last resort after reg fixes and uninstalls failed to allow a successful Office 2013 install. At this point without a disc, I was super frustrated when I couldn’t save to the USB, but am happy that someone knows what they are doing and is willing to help others. Thanks